Avengers: Secret Wars will feature a fan-favorite Stranger Things star. The Marvel Cinematic Universe has had quite a few stacked rosters throughout its long history. When it comes to the MCU’s Avengers movies, which have become crossover events for the entire franchise, several of Hollywood’s biggest actors and a few rising stars are expected to come together with every installment.

Avengers: Doomsday‘s cast illustrates that, bringing back actors from Fox’s original X-Men franchise to stand alongside MCU veterans like Thor star Chris Hemsworth, as well as Multiverse Saga newcomers. While Avengers: Secret Wars‘ story is a secret for now, the Doomsday follow-up will feature Robert Downey Jr.’s Doctor Doom, multiple confirmed MCU heroes, and now a young Stranger Things star.

According to a new report from Deadline, after her mysterious MCU debut in Spider-Man: Brand New Day next year, Sadie Sink will return to the franchise in 2027’s Avengers: Secret Wars. The outlet claims that Sink will be filming Secret Wars later in London in 2026, with a previous report from The Hollywood Reporter claiming the MCU movie would start principal photography in summer 2026.

Sink joins the MCU in Spider-Man: Brand New Day, swinging into theaters on July 31, 2026. While the Stranger Things star will reportedly play a major role in the Marvel movie, Sink’s character remains a mystery. The actress has been rumored for many Marvel characters, ranging from X-Men’s Jean Grey to Spider-Man love interests Gwen Stacy and Mary Jane Watson to more.

Given the report that Sink will be part of Avengers: Secret Wars, it seems that whoever she ends up playing could be a major character in the MCU going forward. That strengthens the speculation that she could be X-Men’s Jean Grey. At 23, Sink could easily stay in the MCU for a decade or more.

The MCU’s X-Men movie is being written by The Ballad of Songbirds & Snakes‘ Michael Lesslie. It will be directed by Thunderbolts*’s Jake Schreier. Casting has yet to be announced, though with Avengers: Secret Wars confirmed to reboot the MCU, it would make sense for Marvel Studios’ version of the X-Men to appear, even if for a cameo at the end.

In May, Sadie Sink addressed her MCU casting rumors, revealing that she saw them and that they were cool to read, saying, “I love the Marvel Universe. I mean they’re awesome rumors.” With the Avengers: Doomsday trailer confirmed for December, the Spider-Man: Brand New Day trailer should not be far behind, potentially revealing who Sink plays in the film and in Avengers: Secret Wars.

Avengers: Secret Wars will be released in theaters on December 17, 2027.